linux/drivers/hwmon/ltc4245.c
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   1/*
   2 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
   3 *
   4 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; version 2 of the License.
   9 *
  10 * This driver is based on the ds1621 and ina209 drivers.
  11 *
  12 * Datasheet:
  13 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
  14 */
  15
  16#include <linux/kernel.h>
  17#include <linux/module.h>
  18#include <linux/init.h>
  19#include <linux/err.h>
  20#include <linux/slab.h>
  21#include <linux/i2c.h>
  22#include <linux/hwmon.h>
  23#include <linux/hwmon-sysfs.h>
  24#include <linux/i2c/ltc4245.h>
  25
  26/* Here are names of the chip's registers (a.k.a. commands) */
  27enum ltc4245_cmd {
  28        LTC4245_STATUS                  = 0x00, /* readonly */
  29        LTC4245_ALERT                   = 0x01,
  30        LTC4245_CONTROL                 = 0x02,
  31        LTC4245_ON                      = 0x03,
  32        LTC4245_FAULT1                  = 0x04,
  33        LTC4245_FAULT2                  = 0x05,
  34        LTC4245_GPIO                    = 0x06,
  35        LTC4245_ADCADR                  = 0x07,
  36
  37        LTC4245_12VIN                   = 0x10,
  38        LTC4245_12VSENSE                = 0x11,
  39        LTC4245_12VOUT                  = 0x12,
  40        LTC4245_5VIN                    = 0x13,
  41        LTC4245_5VSENSE                 = 0x14,
  42        LTC4245_5VOUT                   = 0x15,
  43        LTC4245_3VIN                    = 0x16,
  44        LTC4245_3VSENSE                 = 0x17,
  45        LTC4245_3VOUT                   = 0x18,
  46        LTC4245_VEEIN                   = 0x19,
  47        LTC4245_VEESENSE                = 0x1a,
  48        LTC4245_VEEOUT                  = 0x1b,
  49        LTC4245_GPIOADC                 = 0x1c,
  50};
  51
  52struct ltc4245_data {
  53        struct device *hwmon_dev;
  54
  55        struct mutex update_lock;
  56        bool valid;
  57        unsigned long last_updated; /* in jiffies */
  58
  59        /* Control registers */
  60        u8 cregs[0x08];
  61
  62        /* Voltage registers */
  63        u8 vregs[0x0d];
  64
  65        /* GPIO ADC registers */
  66        bool use_extra_gpios;
  67        int gpios[3];
  68};
  69
  70/*
  71 * Update the readings from the GPIO pins. If the driver has been configured to
  72 * sample all GPIO's as analog voltages, a round-robin sampling method is used.
  73 * Otherwise, only the configured GPIO pin is sampled.
  74 *
  75 * LOCKING: must hold data->update_lock
  76 */
  77static void ltc4245_update_gpios(struct device *dev)
  78{
  79        struct i2c_client *client = to_i2c_client(dev);
  80        struct ltc4245_data *data = i2c_get_clientdata(client);
  81        u8 gpio_curr, gpio_next, gpio_reg;
  82        int i;
  83
  84        /* no extra gpio support, we're basically done */
  85        if (!data->use_extra_gpios) {
  86                data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
  87                return;
  88        }
  89
  90        /*
  91         * If the last reading was too long ago, then we mark all old GPIO
  92         * readings as stale by setting them to -EAGAIN
  93         */
  94        if (time_after(jiffies, data->last_updated + 5 * HZ)) {
  95                dev_dbg(&client->dev, "Marking GPIOs invalid\n");
  96                for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
  97                        data->gpios[i] = -EAGAIN;
  98        }
  99
 100        /*
 101         * Get the current GPIO pin
 102         *
 103         * The datasheet calls these GPIO[1-3], but we'll calculate the zero
 104         * based array index instead, and call them GPIO[0-2]. This is much
 105         * easier to think about.
 106         */
 107        gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
 108        if (gpio_curr > 0)
 109                gpio_curr -= 1;
 110
 111        /* Read the GPIO voltage from the GPIOADC register */
 112        data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
 113
 114        /* Find the next GPIO pin to read */
 115        gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
 116
 117        /*
 118         * Calculate the correct setting for the GPIO register so it will
 119         * sample the next GPIO pin
 120         */
 121        gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
 122
 123        /* Update the GPIO register */
 124        i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
 125
 126        /* Update saved data */
 127        data->cregs[LTC4245_GPIO] = gpio_reg;
 128}
 129
 130static struct ltc4245_data *ltc4245_update_device(struct device *dev)
 131{
 132        struct i2c_client *client = to_i2c_client(dev);
 133        struct ltc4245_data *data = i2c_get_clientdata(client);
 134        s32 val;
 135        int i;
 136
 137        mutex_lock(&data->update_lock);
 138
 139        if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 140
 141                dev_dbg(&client->dev, "Starting ltc4245 update\n");
 142
 143                /* Read control registers -- 0x00 to 0x07 */
 144                for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
 145                        val = i2c_smbus_read_byte_data(client, i);
 146                        if (unlikely(val < 0))
 147                                data->cregs[i] = 0;
 148                        else
 149                                data->cregs[i] = val;
 150                }
 151
 152                /* Read voltage registers -- 0x10 to 0x1c */
 153                for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
 154                        val = i2c_smbus_read_byte_data(client, i+0x10);
 155                        if (unlikely(val < 0))
 156                                data->vregs[i] = 0;
 157                        else
 158                                data->vregs[i] = val;
 159                }
 160
 161                /* Update GPIO readings */
 162                ltc4245_update_gpios(dev);
 163
 164                data->last_updated = jiffies;
 165                data->valid = 1;
 166        }
 167
 168        mutex_unlock(&data->update_lock);
 169
 170        return data;
 171}
 172
 173/* Return the voltage from the given register in millivolts */
 174static int ltc4245_get_voltage(struct device *dev, u8 reg)
 175{
 176        struct ltc4245_data *data = ltc4245_update_device(dev);
 177        const u8 regval = data->vregs[reg - 0x10];
 178        u32 voltage = 0;
 179
 180        switch (reg) {
 181        case LTC4245_12VIN:
 182        case LTC4245_12VOUT:
 183                voltage = regval * 55;
 184                break;
 185        case LTC4245_5VIN:
 186        case LTC4245_5VOUT:
 187                voltage = regval * 22;
 188                break;
 189        case LTC4245_3VIN:
 190        case LTC4245_3VOUT:
 191                voltage = regval * 15;
 192                break;
 193        case LTC4245_VEEIN:
 194        case LTC4245_VEEOUT:
 195                voltage = regval * -55;
 196                break;
 197        case LTC4245_GPIOADC:
 198                voltage = regval * 10;
 199                break;
 200        default:
 201                /* If we get here, the developer messed up */
 202                WARN_ON_ONCE(1);
 203                break;
 204        }
 205
 206        return voltage;
 207}
 208
 209/* Return the current in the given sense register in milliAmperes */
 210static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
 211{
 212        struct ltc4245_data *data = ltc4245_update_device(dev);
 213        const u8 regval = data->vregs[reg - 0x10];
 214        unsigned int voltage;
 215        unsigned int curr;
 216
 217        /*
 218         * The strange looking conversions that follow are fixed-point
 219         * math, since we cannot do floating point in the kernel.
 220         *
 221         * Step 1: convert sense register to microVolts
 222         * Step 2: convert voltage to milliAmperes
 223         *
 224         * If you play around with the V=IR equation, you come up with
 225         * the following: X uV / Y mOhm == Z mA
 226         *
 227         * With the resistors that are fractions of a milliOhm, we multiply
 228         * the voltage and resistance by 10, to shift the decimal point.
 229         * Now we can use the normal division operator again.
 230         */
 231
 232        switch (reg) {
 233        case LTC4245_12VSENSE:
 234                voltage = regval * 250; /* voltage in uV */
 235                curr = voltage / 50; /* sense resistor 50 mOhm */
 236                break;
 237        case LTC4245_5VSENSE:
 238                voltage = regval * 125; /* voltage in uV */
 239                curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
 240                break;
 241        case LTC4245_3VSENSE:
 242                voltage = regval * 125; /* voltage in uV */
 243                curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
 244                break;
 245        case LTC4245_VEESENSE:
 246                voltage = regval * 250; /* voltage in uV */
 247                curr = voltage / 100; /* sense resistor 100 mOhm */
 248                break;
 249        default:
 250                /* If we get here, the developer messed up */
 251                WARN_ON_ONCE(1);
 252                curr = 0;
 253                break;
 254        }
 255
 256        return curr;
 257}
 258
 259static ssize_t ltc4245_show_voltage(struct device *dev,
 260                                    struct device_attribute *da,
 261                                    char *buf)
 262{
 263        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 264        const int voltage = ltc4245_get_voltage(dev, attr->index);
 265
 266        return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
 267}
 268
 269static ssize_t ltc4245_show_current(struct device *dev,
 270                                    struct device_attribute *da,
 271                                    char *buf)
 272{
 273        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 274        const unsigned int curr = ltc4245_get_current(dev, attr->index);
 275
 276        return snprintf(buf, PAGE_SIZE, "%u\n", curr);
 277}
 278
 279static ssize_t ltc4245_show_power(struct device *dev,
 280                                  struct device_attribute *da,
 281                                  char *buf)
 282{
 283        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 284        const unsigned int curr = ltc4245_get_current(dev, attr->index);
 285        const int output_voltage = ltc4245_get_voltage(dev, attr->index+1);
 286
 287        /* current in mA * voltage in mV == power in uW */
 288        const unsigned int power = abs(output_voltage * curr);
 289
 290        return snprintf(buf, PAGE_SIZE, "%u\n", power);
 291}
 292
 293static ssize_t ltc4245_show_alarm(struct device *dev,
 294                                          struct device_attribute *da,
 295                                          char *buf)
 296{
 297        struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
 298        struct ltc4245_data *data = ltc4245_update_device(dev);
 299        const u8 reg = data->cregs[attr->index];
 300        const u32 mask = attr->nr;
 301
 302        return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
 303}
 304
 305static ssize_t ltc4245_show_gpio(struct device *dev,
 306                                 struct device_attribute *da,
 307                                 char *buf)
 308{
 309        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 310        struct ltc4245_data *data = ltc4245_update_device(dev);
 311        int val = data->gpios[attr->index];
 312
 313        /* handle stale GPIO's */
 314        if (val < 0)
 315                return val;
 316
 317        /* Convert to millivolts and print */
 318        return snprintf(buf, PAGE_SIZE, "%u\n", val * 10);
 319}
 320
 321/*
 322 * These macros are used below in constructing device attribute objects
 323 * for use with sysfs_create_group() to make a sysfs device file
 324 * for each register.
 325 */
 326
 327#define LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \
 328        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 329        ltc4245_show_voltage, NULL, ltc4245_cmd_idx)
 330
 331#define LTC4245_CURRENT(name, ltc4245_cmd_idx) \
 332        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 333        ltc4245_show_current, NULL, ltc4245_cmd_idx)
 334
 335#define LTC4245_POWER(name, ltc4245_cmd_idx) \
 336        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 337        ltc4245_show_power, NULL, ltc4245_cmd_idx)
 338
 339#define LTC4245_ALARM(name, mask, reg) \
 340        static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
 341        ltc4245_show_alarm, NULL, (mask), reg)
 342
 343#define LTC4245_GPIO_VOLTAGE(name, gpio_num) \
 344        static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 345        ltc4245_show_gpio, NULL, gpio_num)
 346
 347/* Construct a sensor_device_attribute structure for each register */
 348
 349/* Input voltages */
 350LTC4245_VOLTAGE(in1_input,                      LTC4245_12VIN);
 351LTC4245_VOLTAGE(in2_input,                      LTC4245_5VIN);
 352LTC4245_VOLTAGE(in3_input,                      LTC4245_3VIN);
 353LTC4245_VOLTAGE(in4_input,                      LTC4245_VEEIN);
 354
 355/* Input undervoltage alarms */
 356LTC4245_ALARM(in1_min_alarm,    (1 << 0),       LTC4245_FAULT1);
 357LTC4245_ALARM(in2_min_alarm,    (1 << 1),       LTC4245_FAULT1);
 358LTC4245_ALARM(in3_min_alarm,    (1 << 2),       LTC4245_FAULT1);
 359LTC4245_ALARM(in4_min_alarm,    (1 << 3),       LTC4245_FAULT1);
 360
 361/* Currents (via sense resistor) */
 362LTC4245_CURRENT(curr1_input,                    LTC4245_12VSENSE);
 363LTC4245_CURRENT(curr2_input,                    LTC4245_5VSENSE);
 364LTC4245_CURRENT(curr3_input,                    LTC4245_3VSENSE);
 365LTC4245_CURRENT(curr4_input,                    LTC4245_VEESENSE);
 366
 367/* Overcurrent alarms */
 368LTC4245_ALARM(curr1_max_alarm,  (1 << 4),       LTC4245_FAULT1);
 369LTC4245_ALARM(curr2_max_alarm,  (1 << 5),       LTC4245_FAULT1);
 370LTC4245_ALARM(curr3_max_alarm,  (1 << 6),       LTC4245_FAULT1);
 371LTC4245_ALARM(curr4_max_alarm,  (1 << 7),       LTC4245_FAULT1);
 372
 373/* Output voltages */
 374LTC4245_VOLTAGE(in5_input,                      LTC4245_12VOUT);
 375LTC4245_VOLTAGE(in6_input,                      LTC4245_5VOUT);
 376LTC4245_VOLTAGE(in7_input,                      LTC4245_3VOUT);
 377LTC4245_VOLTAGE(in8_input,                      LTC4245_VEEOUT);
 378
 379/* Power Bad alarms */
 380LTC4245_ALARM(in5_min_alarm,    (1 << 0),       LTC4245_FAULT2);
 381LTC4245_ALARM(in6_min_alarm,    (1 << 1),       LTC4245_FAULT2);
 382LTC4245_ALARM(in7_min_alarm,    (1 << 2),       LTC4245_FAULT2);
 383LTC4245_ALARM(in8_min_alarm,    (1 << 3),       LTC4245_FAULT2);
 384
 385/* GPIO voltages */
 386LTC4245_GPIO_VOLTAGE(in9_input,                 0);
 387LTC4245_GPIO_VOLTAGE(in10_input,                1);
 388LTC4245_GPIO_VOLTAGE(in11_input,                2);
 389
 390/* Power Consumption (virtual) */
 391LTC4245_POWER(power1_input,                     LTC4245_12VSENSE);
 392LTC4245_POWER(power2_input,                     LTC4245_5VSENSE);
 393LTC4245_POWER(power3_input,                     LTC4245_3VSENSE);
 394LTC4245_POWER(power4_input,                     LTC4245_VEESENSE);
 395
 396/*
 397 * Finally, construct an array of pointers to members of the above objects,
 398 * as required for sysfs_create_group()
 399 */
 400static struct attribute *ltc4245_std_attributes[] = {
 401        &sensor_dev_attr_in1_input.dev_attr.attr,
 402        &sensor_dev_attr_in2_input.dev_attr.attr,
 403        &sensor_dev_attr_in3_input.dev_attr.attr,
 404        &sensor_dev_attr_in4_input.dev_attr.attr,
 405
 406        &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
 407        &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
 408        &sensor_dev_attr_in3_min_alarm.dev_attr.attr,
 409        &sensor_dev_attr_in4_min_alarm.dev_attr.attr,
 410
 411        &sensor_dev_attr_curr1_input.dev_attr.attr,
 412        &sensor_dev_attr_curr2_input.dev_attr.attr,
 413        &sensor_dev_attr_curr3_input.dev_attr.attr,
 414        &sensor_dev_attr_curr4_input.dev_attr.attr,
 415
 416        &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
 417        &sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
 418        &sensor_dev_attr_curr3_max_alarm.dev_attr.attr,
 419        &sensor_dev_attr_curr4_max_alarm.dev_attr.attr,
 420
 421        &sensor_dev_attr_in5_input.dev_attr.attr,
 422        &sensor_dev_attr_in6_input.dev_attr.attr,
 423        &sensor_dev_attr_in7_input.dev_attr.attr,
 424        &sensor_dev_attr_in8_input.dev_attr.attr,
 425
 426        &sensor_dev_attr_in5_min_alarm.dev_attr.attr,
 427        &sensor_dev_attr_in6_min_alarm.dev_attr.attr,
 428        &sensor_dev_attr_in7_min_alarm.dev_attr.attr,
 429        &sensor_dev_attr_in8_min_alarm.dev_attr.attr,
 430
 431        &sensor_dev_attr_in9_input.dev_attr.attr,
 432
 433        &sensor_dev_attr_power1_input.dev_attr.attr,
 434        &sensor_dev_attr_power2_input.dev_attr.attr,
 435        &sensor_dev_attr_power3_input.dev_attr.attr,
 436        &sensor_dev_attr_power4_input.dev_attr.attr,
 437
 438        NULL,
 439};
 440
 441static struct attribute *ltc4245_gpio_attributes[] = {
 442        &sensor_dev_attr_in10_input.dev_attr.attr,
 443        &sensor_dev_attr_in11_input.dev_attr.attr,
 444        NULL,
 445};
 446
 447static const struct attribute_group ltc4245_std_group = {
 448        .attrs = ltc4245_std_attributes,
 449};
 450
 451static const struct attribute_group ltc4245_gpio_group = {
 452        .attrs = ltc4245_gpio_attributes,
 453};
 454
 455static int ltc4245_sysfs_create_groups(struct i2c_client *client)
 456{
 457        struct ltc4245_data *data = i2c_get_clientdata(client);
 458        struct device *dev = &client->dev;
 459        int ret;
 460
 461        /* register the standard sysfs attributes */
 462        ret = sysfs_create_group(&dev->kobj, &ltc4245_std_group);
 463        if (ret) {
 464                dev_err(dev, "unable to register standard attributes\n");
 465                return ret;
 466        }
 467
 468        /* if we're using the extra gpio support, register it's attributes */
 469        if (data->use_extra_gpios) {
 470                ret = sysfs_create_group(&dev->kobj, &ltc4245_gpio_group);
 471                if (ret) {
 472                        dev_err(dev, "unable to register gpio attributes\n");
 473                        sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
 474                        return ret;
 475                }
 476        }
 477
 478        return 0;
 479}
 480
 481static void ltc4245_sysfs_remove_groups(struct i2c_client *client)
 482{
 483        struct ltc4245_data *data = i2c_get_clientdata(client);
 484        struct device *dev = &client->dev;
 485
 486        if (data->use_extra_gpios)
 487                sysfs_remove_group(&dev->kobj, &ltc4245_gpio_group);
 488
 489        sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
 490}
 491
 492static bool ltc4245_use_extra_gpios(struct i2c_client *client)
 493{
 494        struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
 495#ifdef CONFIG_OF
 496        struct device_node *np = client->dev.of_node;
 497#endif
 498
 499        /* prefer platform data */
 500        if (pdata)
 501                return pdata->use_extra_gpios;
 502
 503#ifdef CONFIG_OF
 504        /* fallback on OF */
 505        if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
 506                return true;
 507#endif
 508
 509        return false;
 510}
 511
 512static int ltc4245_probe(struct i2c_client *client,
 513                         const struct i2c_device_id *id)
 514{
 515        struct i2c_adapter *adapter = client->adapter;
 516        struct ltc4245_data *data;
 517        int ret;
 518
 519        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 520                return -ENODEV;
 521
 522        data = kzalloc(sizeof(*data), GFP_KERNEL);
 523        if (!data) {
 524                ret = -ENOMEM;
 525                goto out_kzalloc;
 526        }
 527
 528        i2c_set_clientdata(client, data);
 529        mutex_init(&data->update_lock);
 530        data->use_extra_gpios = ltc4245_use_extra_gpios(client);
 531
 532        /* Initialize the LTC4245 chip */
 533        i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
 534        i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
 535
 536        /* Register sysfs hooks */
 537        ret = ltc4245_sysfs_create_groups(client);
 538        if (ret)
 539                goto out_sysfs_create_groups;
 540
 541        data->hwmon_dev = hwmon_device_register(&client->dev);
 542        if (IS_ERR(data->hwmon_dev)) {
 543                ret = PTR_ERR(data->hwmon_dev);
 544                goto out_hwmon_device_register;
 545        }
 546
 547        return 0;
 548
 549out_hwmon_device_register:
 550        ltc4245_sysfs_remove_groups(client);
 551out_sysfs_create_groups:
 552        kfree(data);
 553out_kzalloc:
 554        return ret;
 555}
 556
 557static int ltc4245_remove(struct i2c_client *client)
 558{
 559        struct ltc4245_data *data = i2c_get_clientdata(client);
 560
 561        hwmon_device_unregister(data->hwmon_dev);
 562        ltc4245_sysfs_remove_groups(client);
 563        kfree(data);
 564
 565        return 0;
 566}
 567
 568static const struct i2c_device_id ltc4245_id[] = {
 569        { "ltc4245", 0 },
 570        { }
 571};
 572MODULE_DEVICE_TABLE(i2c, ltc4245_id);
 573
 574/* This is the driver that will be inserted */
 575static struct i2c_driver ltc4245_driver = {
 576        .driver = {
 577                .name   = "ltc4245",
 578        },
 579        .probe          = ltc4245_probe,
 580        .remove         = ltc4245_remove,
 581        .id_table       = ltc4245_id,
 582};
 583
 584module_i2c_driver(ltc4245_driver);
 585
 586MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 587MODULE_DESCRIPTION("LTC4245 driver");
 588MODULE_LICENSE("GPL");
 589
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